A Flash memory card application is driven mainly by consumer electronics products, such as a digital still camera (DSC), cell phone, PDA or MP3 player, toward a smaller form factor and high density. As the form factor becomes smaller while the density requirement grows higher, a need is created for innovative approaches to include as many Flash components into a limited space within the boundary of a particular Flash memory card.
Conventional approaches to pack more density into a Flash memory card are accomplished through wire bonding of one or more Flash memory dies and a Flash controller. A Flash memory die is usually much larger than a Flash controller die in physical size. The Flash memory dies and Flash controller are individually wire-bonded onto a substrate of the Flash memory card.
The substrate usually has interconnecting traces that serve to connect signals among the Flash controller, Flash memory dies and Flash card interface. The substrate is then molded with resin or covered with external casing and made into a finished Flash memory card.
For example, if there are approximately 40 signals and pads on the controller and approximately 20 signals and pads on each Flash memory die, placement constraints are created if both the Flash controller die and Flash memory dies are to be interconnected through wire bonding to the base substrate. Typically 60 pads on the substrate are required for one Flash memory die design and 20 more pads for each additional Flash memory die that is stacked. Therefore, the Flash memory die sizes have to be smaller to leave spaces for the wire bond pads. Furthermore, production yield problems are created due to the necessity of staggering bonding wires from multiple layers of dies.
Accordingly, what is needed is a system and method for providing a high density, small form factor Flash memory card which addresses the above-identified issues. The system should be easy to implement, cost effective and adaptable to existing systems. The present invention addresses such a need.